Legal claims defining the scope of protection, as filed with the USPTO.
1. A system comprising: a forward predictive decision feedback equalizer (pDFE) configured to provide forward Viterbi decoded symbols associated with an input signal; a backward pDFE configured to provide backward Viterbi decoded symbols associated with a time reversed representation of the input signal; and a forward-backward blender adapted to blend the forward Viterbi decoded symbols and the backward Viterbi decoded symbols to provide an output.
2. The system of claim 1 , and further comprising a block based frequency domain filter for filtering the input signal.
3. The system of claim 1 , wherein the forward pDFE includes: a forward Viterbi decoder for generating the forward Viterbi decoded symbols; and a forward feedback filter adapted to provide an estimate of noise in the forward Viterbi decoded symbols, wherein the forward Viterbi decoder is configured to receive data representative of the input signal offset by the estimate of noise in the forward Viterbi decoded symbols.
4. The system of claim 3 , wherein the backward pDFE includes: a backward Viterbi decoder for generating the backward Viterbi decoded symbols; and a backward feedback filter adapted to provide an estimate of noise in the output, wherein the backward Viterbi decoder is configured to receive the time reversed representation of the input signal offset by the estimate of noise in the blended output.
5. The system of claim 4 , wherein the backward Viterbi decoder is selectively configured using metrics obtained from the forward Viterbi decoder.
6. The system of claim 4 , wherein the loading of backward feedback filter symbols is configured using selected portions of the forward Viterbi decoded symbols.
7. The system of claim 1 , and further comprising an input flipper operative to provide the time reversed representation of the input signal, wherein the input flipper is adapted to receive a set of symbols associated with the input signal and store the set of symbols in reverse order.
8. The system of claim 1 , and further comprising an output flipper adapted to store the forward Viterbi decoded symbols in reverse order.
9. The system of claim 8 , wherein the forward-backward blender is configured to blend the reverse order forward Viterbi decoded symbols and the backward Viterbi decoded symbols.
10. The system of claim 1 , wherein the forward-backward blender is configured to blend the forward Viterbi decoded symbols and the backward Viterbi decoded symbols based on comparison of reliability of the forward and backward Viterbi decoded symbols.
11. A method comprising: obtaining forward Viterbi decoded symbols from an input signal; deriving backward Viterbi decoded symbols from a time-reversed representation of the input signal; calculating reliability information for the forward and backward Viterbi decoded symbols; and generating optimized output symbols based on the reliability information.
12. The method of claim 11 , wherein the step of generating output symbols includes blending the forward Viterbi decoded symbols and the backward decoded symbols.
13. The method of claim 12 , wherein blending includes using a forward-backward blender.
14. The method of claim 13 , and further comprising the steps of: providing a time-reversed representation of the input signal using an input flipper adapted to receive a set of symbols associated with the input signal; and storing the set of symbols in reverse order.
15. The method of claim 14 , wherein the forward-backward blender is configured to blend the time-reversed representation of the forward Viterbi decoded symbols and the backward Viterbi decoded symbols.
16. The method of claim 13 , wherein forward-backward blender is configured to blend the forward Viterbi decoded symbols and the backward Viterbi decoded symbols by comparing reliability of the forward and backward Viterbi decoded symbols.
17. The method of claim 16 , wherein reliability of the forward and backward Viterbi decoded symbols is calculated from selected survivor path tallies.
18. The method of claim 13 , wherein forward-backward blender is configured to blend the forward Viterbi decoded symbols and the backward Viterbi decoded symbols based on the reliability information.
19. The method of claim 11 , and further comprising the step of storing the forward Viterbi decoded symbols in time-reversed order using an output flipper.
20. An equalizer comprising: a forward Viterbi decoder for generating forward Viterbi decoded symbols; a backward Viterbi decoder for generating backward Viterbi decoded symbols; a forward feedback filter adapted to provide an estimate of noise in the forward Viterbi decoded symbols; a backward feedback filter adapted to provide an estimate of noise in an output selected from the forward Viterbi decoded symbols and the backward Viterbi decoded symbols; and a forward-backward blender adapted to provide a blended output from the forward Viterbi decoded symbols and the backward Viterbi decoded symbols, wherein the forward Viterbi decoder is configured to receive data representative of an input signal offset by the estimate of noise in the forward Viterbi decoded symbols, the backward Viterbi decoder is configured to receive a time-reversed representation of the input signal offset by the estimate of noise in the blended output, and the forward-backward blender is configured to blend the forward Viterbi decoded symbols and the backward Viterbi decoded symbols by comparing reliability of the forward and backward Viterbi decoded symbols.
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August 23, 2011
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